So often in life I have seen girls end up with the persistent guy, even when they had a closer relationship, more meaningful platonic relationship with another guy, who refused to take risks in terms of pursuing the girls affection.
Look at it this way.
You have two medivacs full of marine marauder and you're contemplating a double pronged drop on the Protoss' two bases. But you're worried, what if there's a couple stalkers and a high templar waiting to feedback at each base?
Obviously, you have to try. That was the whole point of getting quick medivacs and loading them with marines and marauders and positioning them outside the bases of the protoss.
Another thing-- lets suppose that she really just isn't interested in you romantically. You putting your self out there will have the positive side effect that you find out how she really feels,
BUT, it will not destroy your relationship, if you really do enjoy eachothers company, and your personalities enjoy being in close proximity, you will quickly be able to normalize and continue your former friendship, if you want to.